Pathogens can be dangerous to the public. A pathogen is an organism capable of producing an infectious disease in another organism. For example, Escherichia coli O157:H7 (E. coli O157:H7), a foodborne pathogen, is a facultative Gram-negative bacillus, and has been implicated in outbreaks of illness due to ingestion of meats, water, and uncooked fruits and vegetables. E. coli O157:H7 is capable of producing a variety of human illnesses which include hemolytic uremic syndrome and diarrhea. There have been several outbreaks of E. coli O157:H7 food poisoning in the US over the past few decades and the worldwide outbreaks caused by contaminated ground beef.
As another example, Listeri monocytogenes, a foodborne pathogen, is a Gram-positive bacterium known to cause meningitis in newborns. Pregnant mothers are often advised to not eat certain cheeses which may contain Listeri monocytogenes. 
Another example pathogen is Salmonella enteritidis. Salmonella enteritidis is a Gram-negative bacterium known to cause salmonellosis and typhoid fever. Salmonella enteritidis can be foodborne (e.g., raw chicken, undercooked eggs, etc.), or can be transmitted via a fecal-oral route (e.g., via contaminated water and person-person contact). In fact, vacuum cleaner bags have be known to be contaminated with Salmonella enteritidis. 
Current methods for detecting pathogens are time consuming and not very sensitive. Traditionally, detection of pathogens has involved sample collection and enrichment, followed by isolation and identification of the targeted pathogen. Many current detection approaches lack sensitivity and specificity, and often takes 24-96 hours to identify the target pathogen. Current detection devices, such as fiber optic biosensors for example, due to a lack of detection sensitivity, require pre-enrichment of a sample because the target pathogen is present in concentrations below the device's limit of detection. Additional problems associated with current detection methods and devices include high cost and the need for specifically-trained personnel.